This invention relates in general to the construction of sewing machines and to a new and useful method and apparatus for effecting the formation of a pantyhose by sewing it in a continuous seam.
German OS No. 17 60 537 discloses a method of manufacturing wedgeless pantyhose, in which two and two leg parts are superposed, the adjacent inner panty zones are placed below the presser foot on the feeder of the overcast sewing machine and, starting from the upper end of the leg parts, both leg parts are cut open up to the crotch in a single operation and, at the same time, one panty side is sewed together, and upon reversing the motion, the sewing is accomplished by sewing the seam on the other panty side.
In this method, the continuity of operation is interrupted by reversing the motion of the crotch, since shortly before, the sewing speed must be reduced and then the work must be turned into a new position prior to continuing the sewing in the opposite direction, beyond the crotch, while advancing the work.
Since in overcast machines, the cutting knife works at a distance from the needle, which distance is predetermined by the width of the overcast seam, and an exact guidance parallel to the cut edge of the work, which very readily curls in at the edges, is not possible, the provided guidance is such that the edges are cut close ahead of the stitch-forming area, so as to ensure that the cut edges are properly fastened by the overcast stitches. The same is done during the sewing of the second seam, from the crotch to the waist, where the leg parts are already cut open, so that there, material is wasted and the circumferential size of the leg parts in the panty area is reduced. With wedgeless pantyhose, this is a particularly serious disadvantage reducing the quality of the fitting shape.
Since during the formation of the overcast seam, the leg parts in addition are moved through the stitch forming area not in their later position of use but in a position turned thereto through about 90.degree., the overcast seam is thickened to a protuberant beading making the pantyhose uncomfortable to wear.
U.S. Pat. No. 3,621,493 discloses another method of this kind in which two tubular leg parts are superposed, with the seat area being in register, whereupon, starting from the waist rim, the two plies of material are cut open up to the crotch and simultaneously sewed together at their edges each by an overcast seam. This, however, requires a securing seam in the crotch zone, to connect the two separate seams, thus an additional sewing operation. The wearing quality already unfavorably affected by the overcast seam is thereby further impaired.
An objective of the invention is to improve the manufacture of wedgeless pantyhose, by making the operation smoother, and by bettering the wearing properties and thus the quality of the finished article.
Acordingly it is an object of the invention to provide a method of manufacturing pantyhose by means of a sewing machine using hose shaped leg parts which comprises arranging the leg parts in a flat side by side longitudinally extending relationship, cutting each leg part along one edge from the waist rim of its panty area up to a crotch, leaving a remaining leg portion of each leg uncut so as to form upper and lower plies of each leg cut along their inner opposite edges, sewing the cut edges of the laterally adjacent lower plies together from the waist rim to the crotch to form a seam, and deflecting the outer plies outwardly to overlie the remaining leg portions and continuing to sew the seam by sewing in the same direction the edge portions of the upper plies together.
A further object of the invention is to provide a sewing machine which includes a sewing machine foot having two spaced apart toe portions which are engageable at the leg portions of material to be formed at the pantyhose and with deflecting areas for deflecting the upper ply areas of the leg portions upwardly as they are being cut along their adjacent edges to form upper and lower ply areas.
A further object of the invention is to provide a sewing machine which is simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.